Xitron has introduced and now uses a USB interface instead of PCI cards. This make sense going forward for compatibility. $500USD is incredibly cheap for a Harlequin RIP unless it is a very old version. This RIP is the best way to go, just make sure the one you purchase is backed by a manufacturer.
If this is your backup, what is your other device and what RIP do you have driving it? You may have other options.